Agaricales » Nidulariaceae » Retiperidiolia

Retiperidiolia reticulata

Retiperidiolia reticulata (Petch) Kraisit., Choeyklin, Boonprat. & M.E. Sm. 2022, in Kraisitudomsook et al., Mycological Progress, 21(6), 56 (2022).

Diagnosis: Basidiocarps globose to subglobose, 310 mm in diam., covered with white peridium when young (primordial stage), becoming yellowish after drying, completely exposed at maturity, composed of regularly septate monomitic hyphae, 23 μm wide, thin-walled, clamp connections present. Peridioles numerous (2050 peridioles in each peridium), not attached to the peridium wall but imbedded in a mucilaginous matrix, white when young, becoming reddish brown with age, disclike, 11.5 mm in diam., 100150 μm high, covered with tunica (outer melanized coat) that is 30100 μm wide. Peridiole cortex one-layered, hollow at the center, clearly reticulate, brownish hyphae branching from the edge in a netlike fashion (observable under 100 × magnification), main branches 810 μm wide, secondary branches 67 μm wide, tertiary branches 56 μm wide, and quaternary branches 24 μm wide. Basidia common but not easily observed, subglobose, thin-walled, hyaline, averaging 10 × 7.5 μm, with 24 elongate sterigmata that are 35 μm long. Metamorphosed basidia common, hyaline, variable in shape and size, i.e., subglobose, obcordate, obpyriform, pyriform,lageniform, lecythiform, or lanceolate (Figure 4c). Basidiospores abundant, oblong to ellipsoid with obtuse apices, sometimes with apiculus, hyaline, thick-walled (12 μm), 710 × 46 μm (Ave. 8 × 5 μm; Q-ratio = 1.76; n = 20).

            Index Fungorum Number: IF842838

Notes: This species was originally described from Sri Lanka by Petch (1919) who named it Nidularia reticulata. Palmer (1961) later transferred it to the segregate genus Mycocalia based on the morphology of the peridium hyphae. The holotype is presumably stored at the Royal Botanic Gardens in Peradeniya (PDA), but we have been unable to receive information about the specimen after multiple attempts to contact curatorial staff. We examined the isotype deposited at the U.S. National Fungus Collection (BPI703331). Its peridiole morphology matches closely with that of R. reticulata. Unfortunately, the specimen is quite scant and sterile, so basidiospores were not observed. Other historical specimens labeled as Mycocalia reticulata were recorded from Louisiana (USA), Australia, and Panama (mycoportal.org) but no molecular data are available for any of these specimens. Although it is possible that these specimens may represent range extensions for Retiperidiolia reticulata, we suspect that instead they could represent Retiperidiolia aquaphila or other undescribed Retiperidiolia species (also see discussion of R. aquaphila below). Additional sampling and molecular analysis of fresh specimens will be important to determine the distribution of this and other species in the genus.


Figure 1 Rooted phylogram of birds nest fungi (Nidulariaceae) based on maximum likelihood analysis of a multi-locus alignment (SSU, LSU, TEF1, and RPB2) with Squamanitaceae taxa as the outgroup. Colored boxes highlight different genera of the birds nest fungi. Numbers next to nodes indicate ML bootstrap support values followed by BI posterior probabilities. Only bootstrap values 75% and posterior probabilities 0.95 are shown. Taxon names are followed by the isolate number and specimen locality. Type specimens are indicated in bold

Figure 2. Midpoint-rooted phylogram of birds nest fungi (Nidulariaceae) based on maximum likelihood analysis of an ITS rDNA alignment. Numbers next to nodes indicate ML bootstrap support values. Only bootstrap values 75% are shown here. Taxon names are followed by the isolate number and specimen locality. Specimens from Thailand are highlighted with black circles. Type specimens are indicated in bold